Reaction apparatus for carrying out endothermic chemical processes

ABSTRACT

A reaction apparatus comprises a long cylindrical inner tubular wall and a short cylindrical outer tubular wall arranged outside of the inner tubular wall intermediate its length. An annular tube sheet arranged at each end of the outer tubular wall closes the space between the inner and outer tubular walls at the respective ends of the outer tubular wall and a plurality of contact tubes which are adapted to have a catalyst therein extend between the annular tube sheets and are seated in respective ones thereof. The tube sheets at the respective ends are covered to define an inlet for reaction gases which flow through the tubes to the opposite outlet end defined at the opposite end. One end of the interior of the inner tube is partitioned to define a heat carrier expansion chamber and a pump is mounted at this end and has an impeller located within the chamber. The impeller is surrounded by an annular hollow body which defines a discharge passage for the heat carrier medium for flow axially along the inner tubular member toward the opposite end and then for flow through an opening in the inner tubular member over the contact tubes and then back toward the impeller for return through the annular space between the annular hollow body and the inner tubular member.

United States Patent 1191 Wanka et a1.

[ 1 Nov. 26, 1974 1 REACTION APPARATUS FOR CARRYING OUT ENDOTHERMIC CHEMICAL PROCESSES [75] Inventors: Oskar Wanka; Jeno Mihalyi, both of Deggendorf, Donau, Germany [73] Assignee: Deggendorfer Werft und Eisenbau GmbH, Deggendorf/Donau,

Germany [22] Filed: June 18, 1973 [21] Appl. No.: 371,302

[30] Foreign Application Priority Data FOREIGN PATENTS OR APPLICATIONS 1,213,280 11/1970 Great Britain.... 165/107 1,033,223 7/1958 Germany 1 165/107 1,346,421 11/1962 France 122/33 1,044,335 11/1958 Germany .1 165/107 963,913 1/1950 France 23/288 Primary ExaminerManuel A. Antonakas Assistant ExaminerDaniel J. OConnor Attorney, Agent, or Firm-McGlew and Tuttle 57 ABSTRACT A reaction apparatus comprises a long cylindrical inner tubular wall and a short cylindrical outer tubular wall arranged outside of the inner tubular wall intermediate its length. An annular tube sheet arranged at each end of the outer tubular wall closes the space between the inner and outer tubular walls at the respective ends of the outer tubular wall and a plurality of contact tubes which are adapted to have a catalyst therein extend between the annular tube sheets and are seated in respective ones thereof. The tube sheets at the respective ends are covered to define an inlet for reaction gases which flow through the tubes to the opposite outlet end defined at the opposite end. One end of the interior of the inner tube is partitioned to define a heat carrier expansion chamber and a pump is mounted at this end and has an impeller located within the chamber. The impeller is surrounded by an annular hollow body which defines a discharge passage for the heat carrier medium for flow axially along the inner tubular member toward the opposite end and then for flow through an opening in the inner tubular member over the contact tubes and then back toward the impeller for return through the annular space between the annular hollow body and the inner tubular member.

5 Claims, 6 Drawing Figures REACTION APPARATUS FOR CARRYING OUT ENDOTHERMIC CHEMICAL PROCESSES BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates in general to devices for carrying out chemical processes and, in particular, to a new and useful reaction apparatus for carrying out endothermic chemical processes and which includes centrally arranged heating means for a heat carrier which is circulated around contact tubes through which the reaction gases are moved.

2. DESCRIPTION OF THE PRIOR ART The present invention is particularly applicable for use in carrying out endothermic chemical processes using an annular bundle of vertical contact tubes which are adapted to contain a catalyst mass. Reaction gases are directed through the tubes containing the catalyst mass and the heat necessary for the reaction course is supplied by a heat carrier which is circulated over the contact tubes. The heat carrier which is circulated by a pump, delivers heat to the contact tubes and this heat is resupplied by burners at another point.

The principal problem of the present invention is to develop a reaction apparatus which is a compact structure of a closed type and without external portions and which has a symmetry axis and a most favorable flowing course for the heat carrier and the reaction gases and which provides a desirable heat exchange relationship between the different media.

SUMMARY OF THE INVENTION In accordance with the invention, there is provided a reaction apparatus which is formed by a long cylindrical inner tube and a shorter cylindrical outer tube which embraces the inner tube concentrically over a portion of its length. Contact tubes are located in a space between the inner tube and the outer tube and are seated in two sheets which are secured to respective ends of the outer tube and at their interiors to said inner tube. The inner tube is provided with an opening adjacent each end of the space enclosed between the I tube sheets to provide for inflow and outflow of a heat carrier means which is circulated from a heat carrier expansion chamber defined at one end of the inner tubular member by a circulating pump which is positioned in this chamber. Also arranged within the inner tubular member is a relatively short cylindrical wall which is spaced inwardly from the inner tubular member wall to define an intermediate space at a location between the contact tubes and the interior of the inner tubular member.

In one of the embodiment of the invention. a burner is arranged at a closed end of the inner tubular member which is opposite to the expansion chamber for the heat carrier'medium and gaseous products of combustion are circulated in a counterflow arrangement on the interior of the inner tubular member to the flow of the heat carrier medium. The gaseous products of combustion are also circulated in a reverse direction through heating tubes arranged in the interior of the inner tubular member pass the carrier medium which flows in the space surrounding the heating tubes toward the inflow into the contact tube space. In this arrangement the heating tube sheet is formed at one end with a conical end portion for deflecting the heating gases backwardly through the heating tubes. The opposite end is provided with an annular collecting space for the heating gases which are then passed outwardly. In the preferred arrangement an annular hollow body is arranged around the impeller of the circulating pump which is located within the heat carrier expansion chamber, lo cated within one end of the inner tubular member. This hollow body member together with the conical hood define a flow passage for the heat carrier from the impeller to an annular space containing the heating tubes and then from this annular space to an inflow passage defined between the inner tubular member and the space between the annular tube sheets containing the contact tubes.

In another embodiment instead of a burner for supplying the heating, a plurality of electrical rods extend through the inner tubular member from the end thereof which is opposite to the circulating pump. The rods are all held at this end in a switch box for the rods. Tubes advantageously encircle the rods and in one arrangement the ends of the rods are spaced inwardly from the circulating pump in the heat carrier chamber. In another variation, however, the tubes extend along substantially the complete length of the inner tubular member and terminate in a cable connecting box which is mounted on one end of the inner tubular member end.

Accordingly, it is an object of the invention to provide an improved device for carrying out endothermic chemical processes and which includes an inner tubular member and an outer tubular member arranged concentrically with the outer tubular member being spaced outwardly from the inner tubular member and located intermediate its length and carrying tube sheets at each end which are closed against the outer tubular member and which have contact tubes through which reaction gases are passed and wherein the inner tubular member contains a space for a heat carrier medium and a pump for circulating the medium around the contact tubes through ooenings in the inner tubular member provided for this purpose and which also includes heating means for heating the carrier medium which is circulated back to the inner tubular member.

A further object of the invention is to provide a reaction apparatus which is simple in design, rugged in construction and economical to manufacture.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a schematic transverse sectional view of a reaction apparatus constructed in accordance with the invention;

FIG. 2 is a partial sectional view showing a variation of the apparatus shown in FIG. 1;

FIG. 3 is a sectional view taken along the line 33 of FIG. 1;

FIG. 4 is a view similar to FIG. 1 of another embodiment of the invention;

FIG. 5 is a view similar to FIG. 2 of the embodiment shown in FIG. 4; and

FIG. 6 is a view similar to FIG. 1 of still another embodiment of the invention.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in particular, the invention embodied therein in FIGS. 1 and 3 comprises a reaction apparatus which includes a long cylindrical inner tubular wall 1 and a shorter cylindrical outer tubular wall 2 which is shorter than the wall 1 and is arranged around it concentrically thereto intermediate its length. Arranged within the inner tubular wall 1 is an intermediate wall portion 1a which is spaced inwardly from the inner tubular wall 1 and defines therewith a hollow space or intermediate chamber 3.

Each end of the outer tubular wall 2 is closed by an annular tube sheet and 6 respectively which extends to the inner tubular wall 1 at its inside. An annular tube bundle of contact tubes 4 are seated in the respective tube sheets 5 and 6. The exteriors of the tube sheets 5 and 6 are closed by hoods or cover plates 7 and 8 re spectively and an inlet fitting 9 provides for the inflow of reaction gases to the tubes 4 and an outlet fitting 10 at the cover plate 8 provides for the discharge of these gases.

The intermediate chamber 3 is not quite as long as the contact tubes 4 so that it is disposed centrally in respect to the length of these tubes. In the embodiment shown in FIG. 1, orifice plates 11 and 12 are arranged intermediate the lengths of the of the tubes and they are provided with a plurality of perforations which increase in size in a radial direction in order to correspond to the decreasing pressure for the passage of the heat carrier at a controlled rate axially along the length of the contact tubes. The plates may also be provided to provide for flow in a transverse direction of the contact tubes at the end thereof and in a longitudinal direction in the central area.

As shown best in FIG. 3 the inner tube 1 is divided with an opening, for example an annular opening lband 1c adjacent the tube sheet 5 and tube sheet 6 respectively for the inflow and for the outflow of the heat carrier medium. Cylindrical partitions l3 and 14 close off the space between the inner end of an annular hollow body member 15 and the end walls defining the intermediate chamber 3. The annular body member 15 is arranged around an impeller 16 ofa circulating pump 17 for the heat carrier which is circulated in a cycle through the reaction apparatus. The space between the annular hollow body 15 and the inner tubular wall 1 defines a passage 18 for the return flow of the heat carrier and the space between the hollow body inclined inner portion and a conical hood formed as an end to a tube sheet 25 defines an outlet flow passage or pressure passage for the circulating medium which is contained in a circulating medium chamber 19 adjacent an end wall 1d in which is mounted the pump 17.

All of the embodiments of FIGS. 1, 4 and 6 contain the constructive features enumerated above and in the other views similar parts are similarly designated and the differences of the various embodiments are hereinafter indicated.

In the first embodiment according to FIG. 1, there is provided a heating means in the form of a burner 21 which generates gaseous products of combustion in a combustion chamber 20 located centrally within the inner tubular member 1. The burner 21 is mounted in an end wall so that it is accessible from the exterior of the device and the gaseous products of combustion are directed axially in a direction toward the pump 17 until they impinge upon a conical hood 22. Gas heating tubes 24 are seated annular tube sheets 25 and 26 and the combustion gases pass therethrough after being deflected by the conical hood 22 in a reverse direction to the flow of the gases in the combustion chamber 20. A cover 27a extending over the exterior of the tube sheet 26 defines a collection space 27 for the heating gases which exit through an outlet 28. The tube sheet 26 also closes the end of the inner tubular member 1.

When the reaction apparatus indicated in FIG. 1 is operated, the heat consumed by the endothermic reaction due to the flow of the reaction gases through the contact tubes 4 containing the catalyst, is replaced by the heat carrier which is contained in the expansion chamber 19 and which is circulated by the impeller 16 by the pump 17. The circulation is in the direction of the arrows indicated with solid arrowhead portions. The heat carrier medium passes on the pressure side of the impeller 16 through the passage 23 and subsequently through a chamber defined between the intermediate chamber 3 and the combustion chamber 20 for heat exchange with the inner combustion chamber wall and with the heating tubes 24. This brings the heat car rier to its necessary temperature and then it flows through the inlet opening 1c over the contact tubes 14 and into the outlet opening lb and through the passage 18 back to the chamber 19. During the passage of the heat carrier it is distributed uniformly by the perforated plates 11 and 12 for optimum heat exchange flow past the contact tubes 14. The carrier moves in a counterflow direction in respect to the reaction gases so that a particularly efficient heat transfer is possible.

As a heat carrier a salt melt may be used having a vaporization temperature above the operating temperature of 500C. As shown in FIG. 2 the heat carrier may be circulated in the serpentine path indicated by the arrows in an arrangement in which instead of the perforated plates 11 and 12 there are provided alternately arranged annular baffles 29 and 30. The baffles are alternately connected on the inner edge with the hollow body 3 and on their outer edge with the outer tubular member 2.

In the embodiment shown in FIG. 4 the recycle heat carrier is heated by electrical heating rods 31 which are arranged in open tubes 32 which are mounted in a cable connection box 33 arranged at the end of the tubular member which is opposite to the pump 17. These tubes are passed through the closing plate 26 in a sealed manner. The connection box includes a removable cover 34. The upper closed ends of the tubes 32 this embodiment and the remaining flow conditions aresubstantially the same as indicated in respect to FIG. I. A variation shown in FIG. 5 is similar to the variation shown in FIG. 2 and provides the same type of alternate arrangement for the embodiment of FIG. 4.

In the third embodiment shown in FIG. 6, the electrical heating rods 31 and the individual tubes 32' extend upwardly through the annular hollow body and are prolonged up to the closing plate 35 of the inner tube 1. The open ends of the tubes 32 are connected with the closing plate and the heating rods 31 protrude outwardly therefrom into a common cable connection box 33' which is located on the top of the device. The pump 17extends through the connection box 33, In this arrangement the heating rods 31 are arranged in an annular manner and the free central area below the pump 17 and the impeller 16 is provided with a cylindrical displacer or deflector 36 having a diameter substantially equal to thatof the pump housing 17. The displacer 36 includes an upper end in the form of a truncated cone so that it forms together with the sloping surfaces of the annular body 15, a guiding channel for the flow of the heat carrier from the pump impeller 16 to the annular space around the heating tubes 32.

The heating rods 31 are so arranged that they are not heated from the area of the hollow body 15 up wardly because there is either very littler or no heat carrier in the upper portion and so that there is no danger that an overheating of the tubes 32' would take place.

Basically in all the embodiments the recycle of the heat carrier can occur inversely, i.e., in the area of the heating tubes 24 or 32 or 32 in a direction upwardly and in the area of the contact tubes downwardly.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. A reaction apparatus comprising a long cylindrical inner tubular wall, a short cylindrical outer tubular wall shorter than said inner tubular wall located outside of said inner tubular wall and intermediate its length, an annular tube sheet arranged at each end of said outer tubular wall closing the space between said inner and outer tubular walls at respective ends of said outer tubular wall, a plurality of contact tubes adapted to con tain a catalyst extending between and seated in said annular tube sheets at respective ends of said outer tubular wall, inlet means defining an inlet for reaction gases connected to said annular tube sheet adjacent one end of said outer tubular wall for the inflow of reaction gases through said contact tubes, outlet means defining an outlet for reaction gases connected to said annular tube sheet adjacent the opposite end of said inner tubular wall for the outflow of reaction gases, wall means closing each end of said inner tubular wall and defining a heat carrier expansion chamber within said inner tubular wall adjacent one end, a pump having an impeller in said heat carrier expansion chamber for circulating the heat carrier, and an annular hollow body in said heat carrier expansion chamber surrounding said im- .peller and defining a central passage for the discharge of the heat carrier by said impeller through said inner tubular wall, said inner tubular wall having an inflow opening therethrough adjacent said annular tube sheet which is remote from said impeller for the inflow of heat carrier over said contact tube toward said annular tube sheet adjacent said impeller, said inner tubular wall also having an outflow opening adjacent the end which is in proximity to said impeller communicating with the space between said inner tubular member and the exterior of said annular hollow body, and heating means within said inner tubular member for heating said carrier as it is circulated by said pump impeller, said heating means comprising a burner, the interior of said inner tubular wall forming a combustion chamber for the generation of combustion gases by said burner, a heating gas tube bundle arranged between said combustion chamber and said contact tubes having one end communicating with saidcombustion chamber at the end thereof opposite to said burner and an opposite end having a discharge for the combustion gases, and means defining a passage for the heat carrier over said gas heating tubes within said inner tubular member and for flow from said gas heating tubes through the inflow opening over said contact tubes.

2. A reaction apparatus according to claim 1, wherein said combustion chamber includes an end wall adjacent said pump of conical formation, said annular hollow body having sloping walls spaced from said conical combustion chamber wall and defining a heat carrier circulation passage therebetween.

3. A reaction apparatus according to claim 1, including means defining an intermediate chamber within said inner tubular wall between said heating gas tubes and said contact tubes, a partition extending from said heating gas chamber to said annular'hollow body defining an outflow passage from said circulating pump to said heating gas tubes and a return passage from said outflow means to said heat carrier chamber.

4. A reaction apparatus comprising a long cylindrical inner tubular wall, a short cylindrical outer tubular wall shorter than said inner tubular wall located outside of said inner tubular wall and intermediate its length, an annular tube sheet arranged at each end of said outer tubular wall closing the space between said inner and outer tubular walls at respective ends of said outer tubular wall, a plurality of contact tubes adapted to contain a catalyst extending between and seated in said annular tube sheets at respective ends of said outer tubular wall, inlet means defining an inlet for reaction gases connected to said annular tube sheet adjacent one end of said outer tubular wall for the inflow of reaction gases through said contact tubes, outlet means defining an outlet for reaction gases connected to said annular tube sheet adjacent the opposite end of said inner tubular wall for the outflow of reaction gases, wall means closing each end of said inner tubular wall and defining a heat carrier expansion chamber within said inner tubular wall adjacent one end, a pump having an impeller in said heat carrier expansion chamber for circulating the heat carrier, and an annular hollow body in said heat carrier expansion chamber surrounding said impeller and defining a central passage for the discharge of the heat carrier by said impeller through said inner tubular wall, said inner tubular wall having an inflow opening therethrough adjacent said annular tube sheet which is remote from said impeller for the inflow of heat carrier over said contact tubes toward said annular tube sheet adjacent said impeller, said inner tubular wall also having an outflow opening adjacent the end which is in proximity to said impeller communicating with the space between said inner tubular member and the exterior of said annular hollow body, and heating means within said inner tubular member for heating said heat carrier as it is circulated by said pump impeller, said heating means comprising electrical heating rods extending through said inner tubular member, a terminal box to which all of said heating rods extend,

said rods being surrounded by rod carrying tubes which terminate at said switch box, means defining an annular hollow chamber within said inner tubular wall between said heating rods and said contact tubes.

5. A reaction apparatus comprising a long cylindrical inner tubular wall, a short cylindrical outer tubular wall shorter than said inner tubular wall located outside of said inner tubular wall and intermediate its length, an annular tube sheet arranged at each end of said outer tubular wall closing the space between said inner and outer tubular walls at respective ends of said outer tubular wall, a plurality of contact tubes adapted to contain a catalyst extending between and seated in said annular tube sheets at respective ends of said outer tubular wall, inlet means defining an inlet for reaction gases connected to said annular tube sheet adjacent one end of said outer tubular wall for the inflow of reaction gases through said contact tubes, outlet means defining an outlet for reaction gases connected to said annular tube sheet adjacent the opposite end of said inner tubular wall for the outflow of reaction gases, wall means closing each end of said inner tubular wall and defining a heat carrier expansion chamber within said inner tubular wall adjacent one end, a pump having an impeller in said heat carrier expansion chamber for circulating the heat carrier, and an annular hollow body in said heat carrier expansion chamber surrounding said impeller and defining a central passage for the discharge of the heat carrier by said impeller through said inner tubular wall, said inner tubular wall having an inflow opening therethrough adjacent said annular tube sheet which is remote from said impeller for the inflow of heat carrier over said contact tubes toward said annular tube sheet adjacent said impeller, said inner tubular wall also having an outflow opening adjacent the end which is in proximity to said impeller communicating with the space between said inner tubular member and the exterior of said annular hollow body, and heating means within said inner tubular member for heating said heat carrier as it is circulated by said pump impeller, said heating means comprising electrical heating rods extending through said inner tubular member, said heating rods being arranged in an annular pattern within said inner tubular wall, a connection box arranged at the end of said inner tubular wall adjacent said pump, said heating rods extending into said connection box, and a displacement body located centrally within said annular arrangement of said heating tubes. 

1. A reaction apparatus comprising a long cylindrical inner tubular wall, a short cylindrical outer tubular wall shorter than said inner tubular wall located outside of said inner tubular wall and intermediate its length, an annular tube sheet arranged at each end of said outer tubular wall closing the space between said inner and outer tubular walls at respective ends of said outer tubular wall, a plurality of contact tubes adapted to contain a catalyst extending between and seated in said annular tube sheets at respective ends of said outer tubular wall, inlet means defining an inlet for reaction gases connected to said annular tube sheet adjacent one end of said outer tubular wall for the inflow of reaction gases through said contact tubes, outlet means defining an outlet for reaction gases connected to said annular tube sheet adjacent the opposite end of said inner tubular wall for the outflow of reaction gases, wall means closing each end of said inner tubular wall and defining a heat carrier expansion chamber within said inner tubular wall adjacent one end, a pump having an impeller in said heat carrier expansion chamber for circulating the heat carrier, and an annular hollow body in said heat carrier expansion chamber surrounding said impeller and defining a central passage for the discharge of the heat carrier by said impeller through said inner tubular wall, said inner tubular wall having an inflow opening therethrough adjacent said annular tube sheet which is remote from said impeller for the inflow of heat carrier over said contact tube toward said annular tube sheet adjacent said impeller, said inner tubular wall also having an outflow opening adjacent the end which is in proximity to said impeller communicating with the space between said inner tubular member and the exterior of said annular hollow body, and heating means within said inner tubular member for heating said carrier as it is circulated by said pump impeller, said heating means comprising a burner, the interior of said inner tubular wall forming a combustion chamber for the generation of combustion gases by said burner, a heating gas tube bundle arranged between said combustion chamber and said contact tubes having one end communicating with said combustion chamber at the end thereof opposite to said burner and an opposite end having a discharge for the combustion gases, and means defining a passage for the heat carrier over said gas heating tubes within said inner tubular member and for flow from said gas heating tubes through the inflow opening over said contact tubes.
 2. A reaction apparatus according to claim 1, wherein said combustion chamber includes an end wall adjacent said pump of conical formation, said annular hollow body having sloping walls spaced from said conical combustion chamber wall and defining a heat carrier circulation passage therebetween.
 3. A reaction apparatus accOrding to claim 1, including means defining an intermediate chamber within said inner tubular wall between said heating gas tubes and said contact tubes, a partition extending from said heating gas chamber to said annular hollow body defining an outflow passage from said circulating pump to said heating gas tubes and a return passage from said outflow means to said heat carrier chamber.
 4. A reaction apparatus comprising a long cylindrical inner tubular wall, a short cylindrical outer tubular wall shorter than said inner tubular wall located outside of said inner tubular wall and intermediate its length, an annular tube sheet arranged at each end of said outer tubular wall closing the space between said inner and outer tubular walls at respective ends of said outer tubular wall, a plurality of contact tubes adapted to contain a catalyst extending between and seated in said annular tube sheets at respective ends of said outer tubular wall, inlet means defining an inlet for reaction gases connected to said annular tube sheet adjacent one end of said outer tubular wall for the inflow of reaction gases through said contact tubes, outlet means defining an outlet for reaction gases connected to said annular tube sheet adjacent the opposite end of said inner tubular wall for the outflow of reaction gases, wall means closing each end of said inner tubular wall and defining a heat carrier expansion chamber within said inner tubular wall adjacent one end, a pump having an impeller in said heat carrier expansion chamber for circulating the heat carrier, and an annular hollow body in said heat carrier expansion chamber surrounding said impeller and defining a central passage for the discharge of the heat carrier by said impeller through said inner tubular wall, said inner tubular wall having an inflow opening therethrough adjacent said annular tube sheet which is remote from said impeller for the inflow of heat carrier over said contact tubes toward said annular tube sheet adjacent said impeller, said inner tubular wall also having an outflow opening adjacent the end which is in proximity to said impeller communicating with the space between said inner tubular member and the exterior of said annular hollow body, and heating means within said inner tubular member for heating said heat carrier as it is circulated by said pump impeller, said heating means comprising electrical heating rods extending through said inner tubular member, a terminal box to which all of said heating rods extend, said rods being surrounded by rod carrying tubes which terminate at said switch box, means defining an annular hollow chamber within said inner tubular wall between said heating rods and said contact tubes.
 5. A reaction apparatus comprising a long cylindrical inner tubular wall, a short cylindrical outer tubular wall shorter than said inner tubular wall located outside of said inner tubular wall and intermediate its length, an annular tube sheet arranged at each end of said outer tubular wall closing the space between said inner and outer tubular walls at respective ends of said outer tubular wall, a plurality of contact tubes adapted to contain a catalyst extending between and seated in said annular tube sheets at respective ends of said outer tubular wall, inlet means defining an inlet for reaction gases connected to said annular tube sheet adjacent one end of said outer tubular wall for the inflow of reaction gases through said contact tubes, outlet means defining an outlet for reaction gases connected to said annular tube sheet adjacent the opposite end of said inner tubular wall for the outflow of reaction gases, wall means closing each end of said inner tubular wall and defining a heat carrier expansion chamber within said inner tubular wall adjacent one end, a pump having an impeller in said heat carrier expansion chamber for circulating the heat carrier, and an annular hollow body in said heat carrier expansion chamber surrounding said impeller and defining a central passage for the dischaRge of the heat carrier by said impeller through said inner tubular wall, said inner tubular wall having an inflow opening therethrough adjacent said annular tube sheet which is remote from said impeller for the inflow of heat carrier over said contact tubes toward said annular tube sheet adjacent said impeller, said inner tubular wall also having an outflow opening adjacent the end which is in proximity to said impeller communicating with the space between said inner tubular member and the exterior of said annular hollow body, and heating means within said inner tubular member for heating said heat carrier as it is circulated by said pump impeller, said heating means comprising electrical heating rods extending through said inner tubular member, said heating rods being arranged in an annular pattern within said inner tubular wall, a connection box arranged at the end of said inner tubular wall adjacent said pump, said heating rods extending into said connection box, and a displacement body located centrally within said annular arrangement of said heating tubes. 